/*
 * Kiwix Android
 * Copyright (c) 2019 Kiwix <android.kiwix.org>
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 *
 */
package org.kiwix.kiwixmobile.localFileTransfer

import android.content.Context
import org.kiwix.kiwixmobile.core.utils.files.Log
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.delay
import kotlinx.coroutines.isActive
import kotlinx.coroutines.withContext
import org.kiwix.kiwixmobile.localFileTransfer.WifiDirectManager.Companion.copyToOutputStream
import java.io.IOException
import java.net.InetAddress
import java.net.InetSocketAddress
import java.net.Socket

/**
 * Helper class for the local file sharing module.
 *
 * Once the handshake between the two connected devices has taked place, this async-task is used
 * on the sender device to transfer the file to the receiver device at the FILE_TRANSFER_PORT port.
 *
 * It takes in the uri of all the files to be shared. For each file uri, creates a new connection &
 * copies all the bytes from input stream of the file to the output stream of the receiver device.
 * Also changes the status of the corresponding FileItem on the list of files for transfer.
 *
 * A single task is used by the sender for the entire transfer
 */
private const val TIME_OUT = 15000

internal class SenderDevice(
  private val context: Context,
  private val wifiDirectManager: WifiDirectManager,
  private val fileReceiverDeviceAddress: InetAddress
) {
  @Suppress("InjectDispatcher")
  suspend fun send(fileItems: List<FileItem?>) =
    withContext(Dispatchers.IO) {
      // Delay trying to connect with receiver, to allow slow receiver devices to setup server
      delay(FOR_SLOW_RECEIVER)
      val hostAddress = fileReceiverDeviceAddress.hostAddress
      var isTransferErrorFree = true
      fileItems.asSequence()
        .takeWhile { isActive } // checks if coroutine is live
        .forEachIndexed { fileIndex, fileItem ->
          try {
            Socket().use { socket ->
              fileItem?.fileUri?.let {
                context.contentResolver.openInputStream(it).use { fileInputStream ->
                  socket.bind(null)
                  socket.connect(
                    InetSocketAddress(hostAddress, WifiDirectManager.fileTransferPort),
                    TIME_OUT
                  )
                  Log.d(TAG, "Sender socket connected to server - " + socket.isConnected)
                  publishProgress(fileIndex, FileItem.FileStatus.SENDING)
                  val socketOutputStream = socket.getOutputStream()
                  @Suppress("UnsafeCallOnNullableType")
                  copyToOutputStream(fileInputStream!!, socketOutputStream)
                  Log.d(TAG, "Sender: Data written")
                  publishProgress(fileIndex, FileItem.FileStatus.SENT)
                }
              }
            }
          } catch (e: IOException) {
            e.message?.let { message ->
              Log.e(TAG, message)
            }
            e.printStackTrace()
            isTransferErrorFree = false
            publishProgress(fileIndex, FileItem.FileStatus.ERROR)
          }
        }

      isTransferErrorFree
    }

  private suspend fun publishProgress(
    fileIndex: Int,
    fileStatus: FileItem.FileStatus
  ) {
    withContext(Dispatchers.Main) {
      wifiDirectManager.changeStatus(fileIndex, fileStatus)
    }
  }

  companion object {
    private const val TAG = "SenderDevice"
    private const val FOR_SLOW_RECEIVER: Long = 3000
  }
}
